232 COI^TRIBUTIONS FROM THE NATIONAL HEEBAEIUM. 



Leaves broad, not linear; pods 8-12 cm. long, 10-20 mm. thick. 



Leaves thin, ovate or ovate-lanceolate, taper-pointed; corolla lobes pink, the 



hoods white 2. A. (juadrlfolia. 



Leaves rather stiff, oval, ovate, or obovate; corolla lobes white, the hoods purplish. 



9. A. variegata. 

 Leaves scattered or opposite. 



Leaves scattered; juice not milky. Corolla pale or dark orange; plants hairy. 



4. A. tuberosa. 

 Leaves mainly opposite; juice milky. 

 Leaves heart-shaped, clasping, glabrous, wa vy -margined . Corolla gi-eenish pur- 

 ple or decidedly purpUsh 6. A. amplexicaulis. 



Leaves sessile or short-petioled, not clasping. 

 Stems usually much branched above. 



Plants glabrous or nearly so; leaves seldom over 2.5 cm. wide; petioles 4-10 



mm. long; corolla lobes and hoods rose-purple 10. A. incarnata. 



Plants soft-hairy throughout; larger leaves commonly over 2.5 cm. wide; 

 petioles 2-5 mm. long; corolla lobes and hoods pale pinkish. 



11. A. pulchra. 

 Stems normally simple. 



Pods densely woolly, 2-3 cm. thick, usually warty with soft processes, but 

 occasionally smooth. Leaves downy beneath; corolla whitish to dull 



purple, often fading greenish yellow, the hoods darker 6. A. syriaca. 



Pods neither woolly nor warty, usually less than 2 cm. thick. 

 Leaves downy beneath. Corolla lobes and hoods dark purple. 



7. A. purpura scens. 

 Leaves glabrous beneath . 



Leaves sessile, long taper-pointed. Corolla lobes and hoods purplish red. 



8. A. rubra. 

 Leaves petioled . 

 Leaves taper-pointed, ovate; corolla lobes greenish purple, the hoods 



white or pink 3. A. phytolaccoides. 



Leaves oval, ovate, or obovate; corolla lobes white, the hoods purplish. 



9. A. variegata. 



1. Asclepias verticillata L. 



Rather dry open woods; occasional. July-Aug. Widely distributed in N. Amer. 



2. Asclepias quadrifolla Jacq. 



Rather uncommon on wooded hillsides near the Potomac, above Georgetown. 

 May-June. Eastern N. Amer. 



3. Asclepias phytolaccoides Pursh. 



Woodside, June, 1896 {H. W. Oldys). Eastern U. S. 



4. Asclepias tuberosa L. Butterfly-weed. Pleurisy-root. 

 Frequent in dry open places. June-Aug. Widely distributed in the U. S. {A. 



decumbens L.) 

 Used in medicine and cultivated as an ornamental plant. 



6. Asclepias amplexicaulis J. E. Smith. 



Common in open sandy places, especially on the Coastal Plain. May-July; fr. 

 Aug. Eastern U. S. (A. obtusi/olia Mchx.) 



6. Asclepias syriaca L. Common milkweed. 

 Common in open moist ground, especially along highways and in pastures, often 



appearing as if an introduced weed. June-July. Eastern N. Amer. (A. cornuti 

 Decaisne.) 



7. Asclepias purpurascens L. Purple milkweed. 

 Thickets along the Potomac and Rock Creek; occasional. June. Eastern U. S. 



